Unraveling the Effects of Environment, Deficit Irrigation and Genotype on Yield, Sensory Quality and Antioxidants in Tomato: A Multivariate Analysis

Tomato is a high-value crop whose productivity and quality are threatened by climate change in semi-arid Mediterranean areas. This study examined the effects of environment, deficit irrigation (DI), and genotype on tomato yield as well as sensory and antioxidant characteristics. Field experiments were conducted over two consecutive seasons (2023–2024) at two sites in eastern Sicily differing in soil texture (clayey and sandy). Five genotypes— including two old local landraces of long shelf-life tomato and three hybrids—were subjected to three irrigation regimes based on the replenishment of crop evapotranspiration (ETc): 33% (I33, low irrigation rate), 66% (I66, moderate irrigation rate), and 99% (I99, high irrigation rate, control). Yield was maximized in clayey soil (+55% in 2023 and +44% in 2024) and under the I99 regime (48.48 Mg ha−1). Among the genotypes, the most productive were the hybrids HL1 (‘Lycomech’, high-lycopene tomato) and MP (‘Febo’, mini-plum tomato), with yields exceeding 40 Mg ha−1. Overall, old landraces showed lower productivity. Sensory quality (total solids—TS; total soluble solids—TSS; titratable acidity—TA; TSS/TA) and antioxidant quality (total phenols—TPs; flavonoids—Flavs; antioxidant activity—AA) were superior in sandy soil. Regarding irrigation, the highest overall quality was achieved with the I33 regime. The moderate irrigation regime in I66 limited the yield reduction compared to I33 and improved TSS, reducing sugars, TPs, Flavs, vitamin C, and AA compared to I99, although lycopene content decreased. Among the tomato cultivars examined, old local landraces, specifically the ‘Vulcano’ landrace, demonstrated greater stability and drought resilience than the three hybrids, maintaining their sensory and antioxidant quality across different environments and water regimes. Multivariate data analysis, using principal component analysis (PCA) and K-means clustering, was conducted to assess the impact of experimental factors on the studied traits and to identify groupings based on similarities. In conclusion, local landraces of long shelf-life tomato appear better adapted to conditions of low soil water availability than the new hybrids. DI restoring the 66% ETc offers a viable compromise between fruit quantity and quality for these old genotypes, potentially facilitating their reintroduction into sustainable, low-input cropping systems in Mediterranean regions. DI also represents a viable agronomic option for the new hybrids, enabling the maintenance of satisfactory yield and fruit quality levels while simultaneously saving significant amounts of irrigation water.